Hi,
How can i add water/liqued physic to unity myself?i need it.
Unfortunately, you have to write your own simulator either as a plugin or as a standard script and use that. I would recommend searching the internet for a fluid algorithm and basing yours off of that. Then, you will have to iterate through the mesh's vertices A LOT and move them which will more than likely kill your performance.
So, what does this all mean, it means you really can't [ :( ] do realtime fluid in Unity. The only reason a handful games can do it is because the engine is written from start with fluid simulations in mind. Unity 3 will have soft bodies which might get you closer to the actual effect if you don't need the fluid to flow.